Australia’s most prestigious thoroughbred race has been decided in the stewards’ room with State Of Rest winning the $5 million WS Cox Plate after surviving a protest.

Irish raider State Of Rest edged out Anamoe to be first across the line after a stirring duel in the Moonee Valley straight.

But Anamoe’s jockey Craig Williams claimed interference over the final stages cost the three-year-old certain victory in a brilliant weight-for-age contest.

The winning margin in favour of State Of Rest was a long head.

Williams fired in a protest with the hearing lasting more than 20 minutes before stewards dismissed his objection.

In a race that changed complexion on the home turn, State Of Rest charged to the lead only for Anamoe to trail through underneath.

State Of Rest shifted his ground toward the rail, hampering Anamoe but stewards found the interference was not enough to change the result.

The victory continued young Irish trainer’s Joseph O’Brien’s love affair with Australian racing.

He joins his father Aidan O’Brien as a Cox Plate-winning trainer while the 29-year-old has also led in two Melbourne Cup winners.

Verry Elleegant took the minor placing in a race robbed of a major drawcard when early favourite Zaaki was scratched because of an elevated temperature.